[daip] Re: Large experiments, VBGLU, etc.

[Craig Walker]

I agree with Jon that the burden on users, especially users who have 
taken on the burden of a Global observation in the first place, is not 
great.  Also I see very little realistic hope of getting other stations 
to buy us playback units.  We've been trying that for quite a while 
without so much as a nibble.  What I do worry about is the impact on 
correlator operations as this means many previously 1 pass correlations 
will become 3 pass correlations (or 2 in some special cases).  It is for 
this reason that I see this only as a way to deal with a very small 
number of projects.  If we can get to enough playbacks for HSA, then our 
current work load suggests we are talking about approximately 1 project 
a month on average - half globals, half RDV.  If that allows everyone to 
dump tape completely, it sounds like a win to me.

Cheers.

Craig


Jim Ulvestad wrote:
> Yes, it was triggered by the test meeting report.
> 
> The problem is that y'all are talking about accepting disks
> from more stations than we have playbacks for, thus shifting
> the burden from the stations onto the users.  Once we do
> this, we have lost all leverage to get the stations to help us
> out with playbacks if they want to abandon their tape drives.
> 
> Jim
> 
> R. Craig Walker wrote:
> 
>> Jim,
>>
>> Was this triggered by my test meeting report?
>>
>> Jon has been testing the long-unused ability to process large 
>> observations
>> with multiple pass processing to make sure we have a way to handle a 
>> small
>> number of such projects that may come through here for which we do not
>> have enough tape drives.  We have very little realistic prospect of
>> getting more than 14 playbacks so this gives us a way to handle a few big
>> globals and RDVs.  And it may give an alternative that will allow foreign
>> stations to abandon the tapes that are starting not to work very well,
>> causing us considerable pain on correlation.  We certainly don't want to
>> subject smaller projects to this sort of thing while we have an
>> alternative.
>>
>> Cheers,
>>
>> Craig
>>
>>
>>  
>>
>>> Hi all,
>>>
>>> On the VLBA, why are we correlating projects (if we are) with
>>> 13 disk stations, for our 11 disk playbacks.  This makes life
>>> miserable for the users.  Shouldn't we be recording only 11
>>> stations on disk in that case, as I thought we had planned,
>>> and a couple stations on tape?
>>>
>>> Making a large number of users use VBGLU is not conducive
>>> to making the VLBA more user friendly.  For 20-station
>>> RDVs, the geodetic folks can buy us playbacks if they want
>>> to get all 20 stations.  If we can get to 14-station support for
>>> HSA, I'd rather spend another $100K keeping St. Croix from
>>> collapsing than spend it on playbacks, and I bet the RDV people
>>> sure would like to have SC as well.
>>>
>>> I'm copying this to daip because of the work that has been done
>>> on VBGLU and VBMRG recently.
>>>
>>> Jim
>>>
>>>   
>>
>>
>>
>> ---------------------------------------------------------------------
>>    R. Craig Walker            Array Operations Center
>>    cwalker at nrao.edu           National Radio Astronomy Observatory
>>    Phone  505 835 7247        P. O. Box O
>>    Fax    505 835 7027        Socorro NM 87801   USA
>> --------------------------------------------------------------web
>>
>>  
>>


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     R. Craig Walker            Array Operations Center
     cwalker at nrao.edu           National Radio Astronomy Observatory
     Phone  505 835 7247        P. O. Box O
     Fax    505 835 7027        Socorro NM 87801   USA
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